Indy Total Construction

Your lighting and power accessories will almost certainly need new circuits, which mean having sufficient spare fuseways or breakers at the electric panel, or extending the existing service panel. If you intend extending your central heating system, check that the boiler has the extra capacity.

In general, you will probably have to re-route pipes and cables already in the attic.

Attic conversion work should not be undertaken lightly since major structural alterations to the roof are inevitable. That is why it is essential to employ professionals to carry out at least all the initial design work, loading calculations and the necessary structural alterations. Then, if you want to save money, do the less critical parts of the job yourself: building the dividing partitions, cladding the floor and ceiling, installing the electrical circuits and pipe work.

If you do intend carrying out these tasks yourself, and you have any doubts at all regarding your ability to do so, then consult an expert in the particular area. In the final analysis, it may save much frustration, time and cost.

What the job involves

The weight of the floor, partition walls and ceiling of an attic conversion can be quite considerable and that is without the loading imposed by the framework for a dormer and, of course, the furnishings added to the completed rooms. So the very first job that is done when converting the loft is to build a supporting structure that will be able to carry this loading and also provide partial support to the roof, if parts of its original framework have been removed.

It is most unlikely that the original attic joists will be capable of providing the necessary extra support. There are two ways in which a strong floor frame can be made: either extra joists of the same size as the originals are fitted between them, or a completely separate structure is built on top of them, being supported directly by the load-bearing walls. Of the two, the latter is preferable, since it will insulate the rooms below from noise and vibration from the rooms above. It will also prevent damage to the ceiling during the construction stage. However, the available headroom will be reduced.

The separate framework will consist of strong wooden beams called trimmers placed around the edges and at strategic points joists will be fitted between them on metal hangers. Where trimmers and joists pass over intermediate loadbearing walls they are packed out with wood blocks for support.

Once this framework is in place, the necessary modifications can be made to the roof itself – adding extra support struts, dormer frameworks and even, in some cases, loadbearing wood-framed partitions.

The floor is normally clad with tongued-andgrooved plywood sheets — a quickly-laid, flat floor.

It is possible to buy standard size flights of stairs, either of the closed or open tread type and, if at all possible, these should be chosen to save on the expense of having stairs specially made to fit. It may be necessary to add a trimmer joist to the floor at the foot of the stairs for extra strength; another trimmer will be needed in the attic floor to support the top. The opening for the new stairs will be quite large and roomy, requiring several original attic joists to be cut through. Their ends must be supported from the new framework with trimmer joists or metal hangers.

The staircase itself may need cladding along the underside with gypsum board, unless it is of the open-tread variety.

Joists for the ceiling can be nailed- between the original rafters, and if a dormer is fitted they are bolted in place and carried through to support the dormer roof.

The internal walls can be lightweight stud partitions. The frames should be nailed together flat on the floor and then lifted into position where they can be nailed to the floor joists, the ceiling joists and to the rafters or other parts of the structure. Always notch the frameworks to fit over the existing roof members, not the other way round otherwise you will weaken the roof.

While the ceiling and partition frameworks are bare, you can fit all the electrical accessory mounting boxes to battens nailed in place and run in all the cables and any pipe work. Then cut insulation material to fit between the studs and bracing of the walls, the joists of the ceiling and the original rafters.

Wall cladding

Clad the walls and ceilings with foil-backed gypsum- board. This will help insulate the rooms and prevent moisture from passing through the walls into the roof space. The final job is to plaster the walls and decorate.

You will need to be able to get to the rest of the roof for repairs and maintenance to water tanks and pipe work, in addition to using it for storage purposes.

To this end, hatches should be built into the partition frameworks. They can be fitted with plywood panels held by magnetic catches and trimmed with molding.

The way you tackle the job of making an opening in a wall or removing the wall completely in your house, depends on the type of wall it is and its construction.

A load-bearing wall contributes to the strength of the house by supporting some of its structure: a floor/ceiling, an upstairs wall or part of the roof.

A non-load-bearing wall is simply a dividing partition and its complete removal will have no effect on the rest of the house.

Inspect the floor space above it for signs that it supports the joists, or an upstairs wall. Look in the attic, too, to see if any of the roof framework rests on the wall in question.

All external walls are load-bearing and in general any wall at right-angles to the joists will be load- bearing too. Walls that run parallel to the joists are probably non-load-bearing.

Walls may be of brick, concrete blocks or be wood framed. All three types of construction are used for both load-bearing and non-load-bearing walls.

When you make an opening in a wall, no matter how narrow or wide, you must insert a supporting beam or lintel across the opening to take the load of the structure above, even if it is a non-load-bearing wall. The problem is that even by removing a narrow row of bricks or blocks to make room for the be will put the structure at risk.

For a narrow opening like a door, the bond in pattern of the bricks or blocks will tend to make the wall above the opening self-supporting (or self-corbelling) and only a small triangular section of masonry will be at risk. This can be removed, the lintel fitted and the masonry replaced.

With a very wide opening, the self supporting tendency will disappear and a wide area of the wall will be liable to collapse. To prevent this happening. you must support the wall (and sometimes the ceiling on either side) temporarily with heavy wood and adjustable props.

Openings in walls may be spanned by lengths of concrete, steel or wood. Those for fitting over small openings like doors and windows are called lintels; those for spanning wider gaps are called beams. The following are common: Steel Joist — a heavy I or L-shaped girder for spanning very wide gaps in load-bearing walls; Reinforced Concrete Lintel — for internal or solid brick external walls in spans of up to 10ft.

Heavy to lift and often cast on the job site, is the Pre-stressed Concrete Lintel — lighter than reinforced concrete lintels but not suitable for load- bearing walls, except in upper floors. For spans of up to loft, the wood lintel is used in wood framed walls.

In converting an attic the installation of one or more dormer windows will not only provide essential natural light but also increase the headroom over areas of floor that were previously unusable.

In addition to providing windows and extra floor space, with a dormer built up from eaves level, you can site a staircase immediately below it fixed to the external wall of the house, whereas normally it would have to run through the center for there to be enough headroom at the top.

Since several rafters will have to be cut through make the doliner, the framework must be strong enough to support the load previously borne by the cut rafters. It must also have support at floor level unless it is possible to set the framing directly on top of a loadbearing wall. The original attic joists would certainly not be strong enough. However, since a dormer will be put in as part of an attic conversion this is not really a problem. A strengthening framework and extra joists will have to be put in for the new attic floor and this can be made to support the claimer framework as well. This new framework is built directly onto the house load- bearing walls and is completely independent of the original attic joists and ceiling below.

Calculating the loads involved and designing the supporting framework is specialist work for an architect, engineer or a contractor.

The construction of the donuer framework would follow on from constructing the floor support structure. Once the dormer is complete, do the rest of the conversion work. Access to the roof will be needed so that bulky materials can be passed through from the outside after removing a few tiles or slates and cutting an opening in the roofing felt. An access tower and roof ladder are essential.

The first job is to build the framework of the dormer, making sure it is secure before cutting through the original rafters and removing them.

The first sections of framework to be erected are the two corner posts for the outer end of the dormer. There is no need to strip off all the roofing within the dormer area for this initial construction work; remove

only small sections of tiles and pass the framework through. In this way the roof can be kept reasonably weathertight for most of the time.

The corner posts stand on the supporting floor joists below and are linked immediately below rafter level by a horizontal beam. Short wooden studs are nailed between the purlin and the supporting floor beam. The purlin has two purposes: to tie the bottoms of the corner posts together and to support the lower ends of the original rafters when they are cut through. All the construction is toe-nailed to fit.

Next, nail a horizontal beam across the tops of the corner posts. The joists for the top of the dormer can then be fitted: nail their outer ends to the top of the header and pass them right through the roof and bolt them to the rafters on each side for stability.

If the roof of the dormer is to be flat, tapered wooden slats, called furring pieces, are nailed to the tops of the joists so that the roof will have a fall to the front for drainage. If the dormer is to have a pitched roof, a ridge board and additional rafters are installed above the joists.

Before removing the roof from within the dormer framework, fit additional trimmer rafters between the corner posts and the roof ridge bar (or hip rafter if the dormer is a wide one on a hipped roof). Cut shallow notches in the sides of the corner posts to take the ends of these trimmers, and nail in place.

To complete the framework, the roofing must be stripped off. Lift the tiles or slates from the battens, cut out the felt and saw through the battens to expose the joists: cut these off flush with the undersides of the dormer joists and level with the inner face of the new supporting purlin.

Nail vertical studs between the trimmer rafters and the joists above to provide support for the side “cheek” cladding of the dormer, spacing them to take account of the width of the cladding sheets so that their edges always fall on the centerline of a stud.

Complete the framework by adding a wooden subframe to support the window itself. This is usually a horizontal beam set between the corner posts and supported below by short studs nailed to the top of the new purlin, and possibly to the sides of the cut rafters as well. The window will be narrower than the distance between the corner posts, so nail additional studs between the horizontal beam and header to support it at the sides.

The roof is covered first and if it is flat, it is decked with exterior grade plywood, butting the sheets together and nailing them to the supporting joists. To provide support for the flashing, slip a narrow strip of board under the roof at the junction with the dormer and nail it to the original rafters. To provide a certain degree of protection until the job is completed, you can add the first two layers of felt at this stage, taking them up under the original roof and leaving overlaps at the sides and front for finishing off.

Next the sides and front of the framework on either side of the window opening can be paneled in: you can use foil-backed gypsum board for the cheeks. Nail it to the outside of the framework with the foil side outei inost to prevent moisture penetration.

Fit lead soakers beneath the tiles on each side of the dormer; it may actually be easier to do this before cladding the sides, since they will slip in from the ends of the courses without the removal of the tiles.

Before finishing off cladding the sides, add flashing to the front of the dormer below the window-opening, taking it over the top of the frame-supporting beam and down over the roof tiles or slates below.

If tiles are to be used for cladding, nail narrow battens horizontally around the dormer (the spacing being dictated by the tile size). If boarding is used, nail the battens on vertically. Overlapping tiles and boards are nailed on in pattern to keep out rainwater.

Fit window frames made from seasoned wood. A gutter is fixed along the front fascia board with a short down-pipe at one end which can be led down the corner of the dormer to discharge its contents over the roof below.

Having clad the outside of the dormer and glazed the window, finish off inside — this can be done at the same time as building the interior of the attic room.

While the framework is still exposed, however, glass fiber or polystyrene insulation can be fixed between the various frame members at the sides and in the roof before they are clad with drywall or whatever internal wall cladding is being used.